| 초록 |
Thiophene based materials, such as regioregular poly(3-hexylthiophene) have emerged for the most promising polymers in organic photovoltaics. Up to now, the best energy-conversion efficiencies reported in small-area devices approach just 6%. One of the reasons for the low efficiency is the high band gap of conjugated polymer which results in the absorption of UV and green part of the visible range only. Since the wavelengths from 280 to 400 nm amounts to 1.4% of the possible photon flux, biased absorption contributes small photocurrent to photovoltaic. Therefore lowering the band gap of polymer is of crucial importance for increasing the efficiency. In this study, we design new organic polymers based on alternating donor–acceptor copolymers, and the structures of polymers are optimized by using the DFT. From the analysis of the energy level, it is concluded that the new alternating donor-acceptor copolymers have low band gap and these are applicable to highly efficient photovoltaics. |
